In the above described type of winding machines, in order to keep to a minimum the standstill times required for roll replacements, it is known from DE-OS 29 20 707 to cut the web of material in the cylinder cradle at the point when the full roll is pushed out, by means of a separating device provided with a tear-off blade which can raise through the gap between the cylinders. Thereby, the initial portion of a new web created by this separation is kept wrapped around the support cylinder by negative pressure, until a set of new cores is inserted.
From the yet unpublished German patent application 40 03 504 a generic winding machine with support cylinders is known, wherein rolls are supported by springs and freely rotatable on a support which can be moved upward through the gap between the cylinders in the area of the cylinder cradle, these rolls holding the new initial web portion wrapped around the support cylinder. The separation of the web takes place either by means of a cutting knife fastened to the upper end of the support above the rolls, acting on the web as a tear-off edge at the moment when the fully wound roll is pushed out, or by means of a perforating mechanism arranged in front of the first support cylinder and which weakens the web, so that it tears when the fully wound roll is rotated against a braking force.
In both systems, the position of the separation line in the cylinder cradle has to be selected so that the newly inserted core, at any core diameter, can secure the new initial web portion prior to winding. Independently of the core diameter, the separation line is positioned so high in the cylinder cradle, so that cores with the largest diameter can still safely press down on the web end. Therefore, when cores of a smaller diameter are used, a longer, overhanging web piece has to be wound, leading to the formation of undesirable folds around the core.
A further difficulty consists in gluing the new initial portion of the web to the core. If the cores are provided with a trace of adhesive, it requires high technical efforts to position the cores during insertion so that the trace of glue comes in contact only with the new web beginning at the start of the winding operation, without contaminating the support cylinder (DE-OS 35 27 377). In order to avoid this problem, according to the aforementioned German patent application 40 03 504 the adhesive is applied to the web. Using cores with various diameters requires adjusting of the position of the initial web portion provided with the adhesive strip to the respective core diameter prior to the insertion of new cores.